Hot coolant temps.

[Smokey 01]

Now that the weather has heated up my truck wants to run hot. Usually it fluctuates between 190 and 198 but I pulled a trailer the other day with temps around 90 and a 2 mile grade my coolant got up to 215'. I'm wondering if this is normal or if I may have something going wrong. BTW I was only running the programmer and I was keeping boost below 25 pounds.

Thanks

 

[Evan A. Beck]

Swap out the 190°F t-stat for a 180°F model. Just go to your dealer and ask for a t-stat for a 1999 24-valve diesel. It'll help keep things a bit cooler.

 

[MCummings]

That's how ours runs. It has been that way since new. If the temp gets about 5-10* higher, the fan kicks in 100% and cools it right back down.



It's a safe zone. As long as it is not steadily climbing you'll be ok.



This is a pic of when we are towing our gooseneck that weighs 19,000Lbs, plus truck.





Merrick

 

[TPoulsen]

Swap out the 190°F t-stat for a 180°F model. Just go to your dealer and ask for a t-stat for a 1999 24-valve diesel. It'll help keep things a bit cooler.

Is there any reason you couldn't do this on a 04. 5 ?



Tyler

 

[MCummings]

Tell the dealer you want a t-stat for a '99 24V Cummins Turbo diesel.



Then take that T-Stat, and install it in your '04. 5.



The dealer will look at you funny and tell you that it won't work, when we know it will.



This is a "trick" I do often with the Dodge dealer and Cummins dealers.



Merrick

 

[JCasper]

Mine does that also. I was towing a load of hay over the pass, about a 2-3 mile grade. I had a combined weight of 20,500 lbs and it was 98 degrees out. Pulling the grade in 5th gear at 30lbs boost I was doing about 50-55 MPH the temperature gauge started rising but seemed to stop at about 215 or so and stayed there until I went down the other side. My gauge was right about where it is in the picture above. I was worried at first but it seemed to not go any higher so I just kept going.



Joe

 

[Rams-n-Hogs]

Mine runs like that, also, when I'm towing, and going up a grade. 215 is what my aftermarket water temp gauge says, also. I have the probe for that gauge in the #6 cylinder also, which is the hottest part of the motor. I figure when I see it go much hotter than that, I'll start to worry about it. I was a little worried the first time I saw it go that high, though.

 

[rbattelle]

With the warmer weather mine runs warmer too (I don't tow, though). Empty I see 192-196 depending on wind, grade, and speed with ambient temperature above 90. For ambient temps 80-90 I see 189-194, and for ambient temps below 80 I see 185-189.



I run Fleetguard Compleat ES PG, by the way.



Ryan

 

[Benson]

Anyone have the Cummins part number for that stat?

 

[Smokey 01]

Cummins part NO 3967195.

I just put mine in today and I like it, now I see 190 max.

 

[TJarecke]

My buddy's 03 ran the same way this past weekend pulling my brothers 99 to Platte City and back through KS. One the edge attitude monitor it would hit 215 going up some hills and going through towns.



Is there any disadvantage to the 180 thermostat in the winter?



He will be happy to hear about this mod.

 

[Smokey 01]

I don't see there being much of a disadvantage in winter if any. It is very easy to do and onl;y takes like half a gallon to fill the coolant back up.

 

[rbattelle]

Of course, the hotter the engine runs the more efficient it is.



Ryan

 

[MCummings]

I've said it before, that I would like to see water temps in the 210* -220* range with higher a pressure cooling system, bigger fan, and bigger radiator to keep the engine up to temp, and cool when towing...



Merrick

 

[schRAM]

I have also seen higher temps the last month, was towing an empty 16' horse trailer when i first noticed the higher reading and now i can easily see 216 (edge monitor) with an unloaded truck. It's never done that before even in 90 deg. heat. Replaced t-stat after checking on the stove and noticed that the aftermarket one opened more so i put the new one in ($30). Didn't make a difference after doing so. Removed my edge and made an appointment to have fan clutch checked as well as my a/c, since it has gone downhill as well.

 

[rbattelle]

I've said it before, that I would like to see water temps in the 210* -220* range with higher a pressure cooling system, bigger fan, and bigger radiator to keep the engine up to temp, and cool when towing...

I agree, except for the higher pressure part. Although higher pressure increases your boilover margin. An iron engine can take A LOT of heat without damage. Aluminum engines... not so much.



Ryan

 

[Latenight6]

My Truck Does The Same Thing Hits 215-217

 

[JasonCzerak]

unloaded, edge and ez turn up for speed, the most I see is 208 from 0 -108.



Now once I let her idle for a bit, let things really cool down (EGTs 285-ish). while I was at the track. at the end of the 1/8 the monitor was beeping at me with 212... silly t-stat take a while to open and circulate.



What do you guys running LOTs of boost and fuel get for temps for unloaded racing?

 

[nickleinonen]

I've said it before, that I would like to see water temps in the 210* -220* range with higher a pressure cooling system, bigger fan, and bigger radiator to keep the engine up to temp, and cool when towing...



Merrick

diddo. . i'd like a 200*-205* t-stat in my engine...

 

[John Robinson]

215-220 is not hot for a 3rd gen. that just means she`s working. Cummins is aware of these temps and says its more efficient